1. Technical Field
The disclosure relates to electrical lighting devices, and more particularly to an illumination system providing an uniform illumination pattern, lens and LED module used in the illumination system.
2. Description of the Related Art
For years, people have used traditional incandescent or fluorescence lighting apparatus in order to address their interior lighting concerns. However, such lighting apparatus presents a number of drawbacks. For example, the popular halogen apparatus presents the following drawbacks, such as relatively high power consumption, inefficiency of light dispersion due to the placement of its metal shield in the line sight of the halogen bulb, and its limited effectiveness in preventing glare from the halogen bulb.
Recently, a number of LED lighting apparatuses have been designed to replace the halogen apparatus, as well as other traditional incandescent or fluorescence lighting apparatuses. But, due to mediocre light output, LED used in the past was primarily limited to applications where only small surface areas were illuminated. In these applications the light was concentrated into a narrow beam using an optic designed to take the wide angle light output of an LED and collimate it using a lens, discussed below with respect to FIG. 11. FIG. 11 shows a traditional light illumination system. The light illumination system includes an illuminated area 1, and a LED light module 2 positioned beside the illuminated area 1. The LED light module 2 has a light emitting surface 3 and light 4 emitted forward of the light emitting surface 3 illuminate the illuminated area 1. Understandably, regardless of where the LED light module 2 is disposed with relationship of the illuminated area 1, part of the light 4 illuminate the illuminated area 1 which is closer to the LED light module 2 and the other illuminate the illuminated area 1 which is farther to the LED light module 2. Since the performance of the above illumination is inevitable, part of the light 4, which illuminate the illuminate area 1 and is farther to the LED light module 2, has more attenuation than the other which illuminate the illuminate area 1 and is closer to the LED light module 2. However, the light 4 emitted from the light emitting surface 3 has same initial light intensity. As a result, the illumination value of the illuminated area 2 varies with the distance between the illumination area 1 and the LED light module 2. Examples of some applications of the light illumination system include exhibition hall, showcase, and so on. These new applications require different optical designs. In particular these applications require uniform illumination in the illumination area 2 for improving the sense of quality of the showed products to people.